1. Field of the Invention
This invention relates to an image heating apparatus for use as a fixing device of a copying apparatus or a printer.
2. Related Background Art
Generally, an image heating apparatus of this kind has a heater supplied with electric power from a commercially available power source and generating heat, and is temperature-controlled so that a temperature of this heater or a temperature of a fixing roller heated by this heater may maintain a predetermined level.
However, when there is present an illuminator or the like supplied with electric power from the same plug receptacle as the heating apparatus, there has been the possibility of a flicker phenomenon of the illuminator or the like flickering being caused by a sudden increase or decrease in voltage by the changeover for the conduction or shut-off from the commercially available power source to heating means, depending on the impedance of the power source.
The present invention has been made in view of the above-noted problem and an object thereof is to provide an image heating apparatus which can suppress the flicker occurring to an illuminator or the like.
Another object of the present invention is to provide an image heating apparatus having:
a heater;
power supply means for supplying electric power to the heater; and
time constant setting means for setting a time constant when the power supply means starts the supply of the electric power to the heater, the time constant setting means setting the time constant in conformity with a shut-off time of the supply of the electric power to the heater.
Still another object of the present invention is to provide an image heating apparatus having:
a heater; and
power supply control means for controlling electric power supply to the heater;
wherein the power supply control means shuts off the electric power supply from an electric power supplying state so that an applied voltage to the heater may drop at a predetermined time constant.
Yet still another object of the present invention is to provide an image heating apparatus having:
a heater; and
power supply control means for controlling electric power supply to the heater;
wherein the power supply control means starts the electric power supply so that an applied voltage to the heater may rise at a predetermined time constant, and shuts off the electric power supply from the electric power supplying state so that the applied voltage may drop at a predetermined time constant.
A further object of the present invention is to provide an image heating apparatus having:
a heater;
power supply means for supplying electric power to the heater; and
time constant setting means for setting a time constant when the power supply means starts the supply of the electric power to the heater, the time constant setting means setting a greater time constant during a standby operation than during an image heating operation.
Further objects of the present invention will become apparent from the following detailed description when read with reference to the accompanying drawings.